1. Field of the Invention
The present invention relates to exposure using an electron or ion charged beam. More specifically, the invention relates to exposure of an arbitrary pattern under a condition of constant and periodical arrangement of wirings, standard cells and the like of a semiconductor apparatus.
2. Description of the Related Art
An electron-beam exposure technique enables processing of fine patterns of not more than submicron-meter which cannot be produced by photolithography. For this reason, the electron-beam exposure technique is becoming essential for a semiconductor processing technique which requires refining, high-integration and complication.
In variable shaped beam (VSB) exposure which is a typical electron-beam exposure method, a mask is not required for exposure regardless of pattern forms. In the VSB exposure, since exposure is repeated by dividing a pattern into a lot of minute rectangular shots, the exposure takes longer time, and there is a disadvantage that throughput cannot be obtained.
In order to heighten the throughput, character projection (CP) exposure technique (partial collective exposure), which is capable of, collectively shooting a pattern having a certain size, is devised. In the CP exposure technique, an electron beam emitted from an electron gun is shaped into a rectangle by a first aperture. A desired character is selected from CP apertures having plural character shapes formed on a CP aperture array. The electron beam shaped into the rectangle is shaped into the desired character form. Finally, the electron beam having the character form is reduced so as to be emitted onto a desired portion of a sample. In the CP exposure, portions (character section) of plural desired patterns are created on the aperture array, and exposure is successively carried out for each character created on the aperture array. As the character, a pattern which is exposed repeatedly many times is selected. However, in this CP exposure, a mask should be created for each pattern. Namely, in the case where similar patterns are different partially, one aperture cannot be used commonly. For this reason, the variable shaped beam exposure is also used, and sufficient throughput cannot be obtained. Further, in this CP exposure, there arises a problem that thermal expansion warpage of a mask, which occurs when an electron beam is emitted to the mask, is large and pattern position accuracy is lowered.
In addition, an electron-beam mask transfer system is also suggested. This uses a mask including all desired patterns instead of CP aperture array so as to collectively transfer the patterns. This electron-beam mask transfer system has a problem that mask production costs an enormous amount of money.
A blanking aperture array (BAA) system is also suggested. This uses an array where not less than hundreds of thousands of apertures, which can deflect an electron beam passing therethrough by means of an electric signal, are arranged into a lattice form, and creates a desired beam shape by means of signal control. However, this BAA system has a problem that an apparatus for controlling signal of the BAA section is very expensive.